This story may sound a bit bizarre but actually is true.
In the 1989 a U.S. Air Force veteran requested copies of his dental treatment records from the Department of Veterans Affairs Medical Center in New Hampshire. He believed he had dental treatment at this facility in 1981 and
“….sought his dental records because he believed an electronic eavesdropping device had been planted in his mouth after his wisdom teeth were removed.”
Unfortunately at this time the medical records were on paper and the dental records never turned up.
So I guess this begs the question of whether or not a listening device can be planted in a tooth extraction socket. I think the technology may be there and it may be possible but I highly doubt this a common occurrence.
I suppose this could be possible with a radio-frequency identification (RFID) microchip and there could even be Global Positioning System (GPS) tracking capabilities. This could allow for someone to observe and hear everything the person with the chip hears via a microphone and also know their exact GPS position in the world.
There are certainly many ethical issues raised with such a device and certainly possible negative health effects such as cancer. Even so as technology advances in the future this is certainly a cause for concern. Involuntary microchipping certainly should not be occurring.
Additional information can be found on https://en.wikipedia.org/wiki/Microchip_implant_(human)
Source: James M. Mooney v. Veterans Administration, No. 90-1628, United States Court of Appeals for the First Circuit, December 3, 1990.